LAS VEGAS, Nevada (CNN) -- Democratic front-runner Sen. Hillary Clinton fought back at criticism from some of her presidential rivals Thursday night, decrying what she termed mudslinging and defending her record against the charge that she avoids taking firm positions on controversial issues.

Sen. Hillary Clinton, D-New York and Sen. Barack Obama, D-Illinois.

"The American people know where I've stood for 35 years," Clinton said during a CNN-sponsored debate at the University of Nevada-Las Vegas.

"This is going to be one of the most important elections we've ever had in our country's history, and it is important that we have a candidate who is tested as a president who is ready to lead from day one."

With moderator Wolf Blitzer serving as ringmaster and referee, the candidates sparred over health care, Social Security, illegal immigration, the war in Iraq and foreign trade.

Clinton, running far ahead in the national polls, has come under sharper attack in recent weeks from her opponents, a fact she acknowledged at the beginning of Thursday's debate by saying she had worn an "asbestos" pantsuit.

Sen. Barack Obama of Illinois -- Clinton's closest rival -- went on the offensive, saying that "what the American people are looking for right now is straight answers to tough questions, and that is not what we've seen out of Senator Clinton on a host of issues." Watch audience reactions influence debate »

On Iraq, Obama said he wanted to talk to friends and enemies alike to end the war.

"That's why we can get our troops out -- our combat troops out within 16 months. That's why we have to initiate the kind of regional diplomacy, not just talking to our friends, but talking to our enemies, like Iran and Syria, to try to stabilize the situation there," Obama said.

"It seems that John wants to start a class war. It seems that Barack wants to start a generational war. It seems that Sen. Clinton, with all due respect on her plan on Iraq, doesn't end the war," Richardson said.

"All I want to do is give peace a chance," he said.

Some of the candidates further back in the pack also decried the wrangling between Clinton, Edwards and Obama.

"The American people don't give a darn about any of this stuff that's going on up here," said Sen. Joe Biden of Delaware.

Sen. Chris Dodd of Connecticut said that "when a campaign is about turning up the heat or who's angrier or who's yelling louder, the American people turn off."

Responding to a question on education, Richardson decried underpaying teachers and what he called disrespect for teachers.

"We underpay them," he said. "I would have a minimum wage for all teachers starting out at $40,000 a year."

Meanwhile, Rep. Dennis Kucinich of Ohio accused Edwards of voting to open Chinese trade and bearing some responsibility for dangerous imported Chinese products.

"John, you voted for China trade, understanding that workers were going to be hurt," Kucinich said.

Thursday's event was the first debate of the campaign season in Nevada, a key battleground state with a large Latino population that will hold Democratic caucuses on January 19.

Clinton has a large lead over her rivals among Nevada Democratic caucus-goers, according to a CNN/Opinion Research Corp. poll released Wednesday.

Answering a question from the mother of a U.S. soldier concerned that the United States might go to war against Iran, Clinton defended her vote for a Senate resolution declaring Iran's Revolutionary Guard a terrorist group.

Critics charge it could be used by President Bush as a green light for an attack.

Clinton said that while she opposed any "rush to war," there was "no basis" for the fear that the Senate resolution authorized an attack on Iran.

"The Iranian Revolutionary Guard has assisted the militias and others in killing our Americans and maiming them [in Iraq]," she said. "They have imported technology and technical assistance. I believe they are a terrorist group."

Obama -- who missed the Senate vote on the resolution but has said he opposes it -- said the problem with the measure was that it went beyond identifying the Revolutionary Guard as a terrorist organization.

Republican National Committee Chairman Robert Duncan took a broad swipe at Clinton after the debate.

"Let's hope voters didn't bet on Hillary Clinton clearing up her contradictory statements in Las Vegas," Duncan said in a written statement. "From driver's licenses for illegal immigrants to free trade, from national defense to Social Security, her statements all stand in stark contrast to her record."E-mail to a friend